Going solar
Solar + battery: when does it make sense?
6 min read
A battery roughly doubles the cost of going solar — but it also unlocks three things solar alone can't: power during outages, time-of-use arbitrage, and meaningful energy independence. Whether the math works for your home depends on your utility's rate plan, how often the grid goes down in your area, and what you want from the system.
What a battery actually does for you
- Backup power during outages — the biggest reason most Texas homeowners add storage. A single Powerwall 3 (13.5 kWh) typically runs essentials for 12-24 hours; whole-home backup with HVAC needs 2-3 batteries.
- Time-of-use arbitrage — if your utility charges more during peak hours (typically 4-9 PM), you discharge the battery during peak instead of buying. Annual savings of $200-$600 on the right rate plan.
- Energy independence — using your own solar at night instead of selling it back at a discount, especially in markets without full retail net metering.
- Storm preparedness — Texas grid outages happen — winter storms, summer heat waves, hurricanes. A battery is the difference between cooking on a grill and the lights staying on.
When the math works
- You're in a market without full retail net metering (most of Texas). You'd lose money exporting to the grid; the battery captures that value instead.
- Your utility offers a time-of-use rate plan with a meaningful peak/off-peak spread.
- You have critical loads (medical equipment, well pump, work-from-home setup) where outage costs are real.
- You want whole-home backup and are willing to install 2+ Powerwalls or 3+ Enphase modules.
When the math doesn't work yet
- Your utility offers full retail net metering and a flat rate. Solar without a battery already captures all the value.
- Your area has very few outages and you're fine running off the grid when it goes out.
- You want to minimize lifetime cost and don't need backup. A battery-ready system you add to later is the right play.
Battery sizing 101
| Goal | Battery size | Approximate cost |
|---|---|---|
| Essentials only (lights, fridge, internet) | 1× Powerwall 3 or 1× Enphase IQ 5P | $13k–$15k |
| Whole home except AC | 2× Powerwall or 2× Enphase IQ | $22k–$26k |
| Whole home including AC | 3× Powerwall or 3–4× Enphase IQ | $35k–$45k |
Common questions
Frequently asked
- How long does a battery last?
- Tesla Powerwall 3: 10-year warranty on unlimited cycles, real-world life expected at 12-15 years. Enphase IQ Battery 5P: 15-year warranty. Both are designed to outlive a typical homeowner's stay in the house.
- Can I add a battery later?
- Yes. Every Kaizen install is battery-ready by default — the inverter and electrical setup are pre-configured. Adding a battery in year 5 is straightforward.
- Tesla Powerwall vs. Enphase IQ Battery 5P — which is better?
- Powerwall 3 is the simpler, cheaper-per-kWh choice for whole-home backup. Enphase IQ 5P is modular (start with one, add more), pairs natively with Enphase microinverters, and has a longer 15-year warranty. We walk through both during your design.